This invention relates to reinforced seamless intermediate transfer members. More particularly, this invention relates to seamless reinforced intermediate transfer members for electrostatic transfer of a toner image, comprising a reinforcing member with filler material on, around or embedded in the reinforcing members and electrical regulating materials and methods of making the same.
Intermediate transfer members are well known and have been used extensively in electrophotographic imaging systems. For example, in dry electrophotographic printing machines, multicolor copying has been achieved with the utilization of an intermediate roller as disclosed in U.S. Pat. No. 3,957,367. In devices of this type, successive toner powder images are transferred in superimposed registration with one another, from the photoconductive drum to an intermediate roller. The multicolored image is then transferred to a copy sheet.
An example of a commercial machine which uses an intermediate transfer belt to generate one full color print is the Sharp CX 7500. The Sharp CX 7500 comprises a single photoreceptor. An intermediate transfer member is supported for movement in an endless path such that incremental portions thereof move past the photoreceptor four times enabling sequential transfer of four different color toner images to the intermediate transfer member in superimposed registration with one another.
Other examples of apparatuses using belts as intermediate transfer members can be found in U.S. Pat. Nos. 4,684,238; 4,690,539; 4,183,658; 5,099,286; and 5,119,140.
It has been a goal of workers in this art to develop a seamless intermediate transfer member which optimally satisfies both desirable mechanical properties, such as tensile modulus as well as desirable electrical properties such as surface and bulk resistivity. Such a seamless member also would provide a more reliable electrophotographic imaging device since there would be no mechanical failure of the member at the seam, no thickness increase to cause clearance problems or motion noise and no undesirable toner build-up at the seam.
Many belts are formed by molding or lamination. Such molding is carried out in complex and expensive molds. Molded articles contain flashings that require removal to achieve a smooth outer surface. Laminated belts are usually prepared by applying alternate layers of thermoplastic sheets and reinforcing fabrics. These materials are relatively thick and stiff, and are not suitable for extended cycling over small diameter pulleys or rolls. Belts also have been prepared by welding opposite ends of sheets together to form belts having an undesirable seam which projects above the surface of the belt.
The resulting welded seam on the intermediate transfer member disrupts the continuity of the outer surface of the intermediate transfer member and must be indexed so that it does not print out during an imaging cycle. In other words, efficient stream feeding of paper and throughput are adversely affected because of a necessity to detect a seam within the length of each sheet of paper. Seam detection is a particularly vexing problem for smaller copier and printer designs. A mechanical and optical device is required for indexing the seam and adds to the complexity and cost of copiers, duplicators and printers, and reduces the flexibility of design. Welded belts also are less desirable for electrophotographic imaging systems because the seam forms a weak point in the belt and also collects toner debris during cleaning, particularly with wiper blade cleaning devices. The seam and wiper blade interaction also causes a disruption in motion quality which impacts registration and timing in applications where multiple images must be closely referred to each other.
Examples of intermediate transfer members can be found in U.S. Pat. No. 5,110,702 which discloses an intermediate transfer roll for nonelectrostatic transfer of toned images and U.S. Pat. No. 3,893,761 which discloses an intermediate transfer belt having a polyimide film substrate coated with 0.1-10 mils of silicone rubber or a fluoroelastomer.
U.S. Pat. Nos. 4,684,238 and 4,690,539 disclose intermediate transfer belts composed of polyethylene terephthalate or other suitable polypropylene material.
U.S. Pat. No. 5,119,140 discloses a single layer, non-reinforced intermediate transfer belt preferably fabricated from clear Tedlar, carbon loaded Tedlar or pigmented Tedlar. Such single layer, non-reinforced transfer belts have the disadvantage that their dimensions can change during the printing process resulting in image distortion printed substrates.
U.S. Pat. No. 5,099,286 discloses an intermediate transfer belt comprising electrically conductive urethane rubber reportedly having a volume resistivity of 103 to 104 ohm-cm and a dielectric layer of polytetrafluoroethylene reportedly having a volume resistivity equal to or greater than 10.sup.14 ohm-cm. These volume resistivities can lead to equal electrical potentials over the whole belt when a potential is applied at any point along the belt. This makes it impossible to generate different potentials in different areas along the belt for effective tandem image toner transfer.
None of these patents disclose or suggest an intermediate transfer member having both good mechanical properties and good electrical properties.
Consequently, there is still a need for a seamless intermediate transfer member having improved mechanical as well as electrical properties.